ordinal data: showing relative
differences in quantities as well as kind

interval data: is information
that can be arranged using a standard scale along which operations of addition
and subtraction have meaning. Temperature is an example of an interval measure.

ratio data:

is information that, like interval data, can be arranged
along a scale but, in addition, the scale begins at a non-arbitrary zero
point. At the zero point, no features are present. The operations of multiplication
and division can be employed with ratio data to consider proportions and
magnitudes. Elevation above sea level, precipitation, and population are
all examples of ratio data.